1. Field of the Invention
The present invention relates to an ink jet recording apparatus mountable on or connectable to a copying machine, a printer, communication equipment, or information equipment and a recovery method of a recording head applicable thereto. Particularly, the present invention is effective for a compulsory recovery mechanism (either electrical or mechanical) in a device having heat generating elements for forming bubbles in the ink generating thermal energy and a driving circuit for driving them with an electrical pulse signal.
2. Related Background Art
As fundamental inventions for forming bubbles with thermal energy, there are those as driving a heat generating resistor with an electrical pulse signal, or using optical energy, and in addition, having elements for converting the optical energy to heat, as described in U.S. Pat. No. 4,740,796 or West German Offenlegungshrift No. 2,843,064.
In the field of ink jet recordings, the recovery process called a predischarge is performed as a process for discharging the ink from an outlet in other than recording. As the invention for accomplishing this predischarge with an appropriate exhaust of ink including the in-recording or waiting, there is known U.K. Patent No. 2,169,855. In this official gazette, the recovery performed during usual recording as the predischarge is specifically described and stated expressly as the invention.
On the other hand, for the recovery of a recording head in an extreme state, the recovery using a pump ordinarily called suction recovery has been put to practical use, but there is a disadvantage in accomplishing a smaller, lighter or less expensive apparatus because of its complex construction. Also, in U.S. Pat. No. 4,977,459 disclosing that a proper recovery processing is executed in accordance with the state of a recording head, the final compulsory recovery adopts suction recovery, but not predischarge.
Also, a conventional predischarge is performed in an ordinary discharge condition for recording or its similar condition because it is relatively frequently operated. This is to extend the life of heat generating elements for the recording head. The predischarged ink is discharged toward an ink absorbing member, but in addition, specific paper, recording sheet, foam material, and a cap for recording head are known as the ink receiving member.
However, particularly in the bubble jet recording apparatus that forms flying ink droplets by producing ink bubbles by the use of the thermal energy among such ink jet recording apparatuses, the recording quality tends to degrade in a long term of recording.
Thus, as its cause, it is known that dyes or contaminants in the ink are solidified on a face of the heater which is an electricity-heat converter for supplying the thermal energy to the ink, due to the heat, and accumulated thereon. Therefore, large efforts have been made to remove contaminants, such as refining of dyes, so that such deposits may not be produced on the heater face, but there are some cases of making it difficult to use the recording head, because the recording quality is degraded, irrespective of almost no deposits on the heater face in a long term of recording using such ink, and there are no sufficient resolutions for that problem.
Particularly when the recovery can not be made only with a pump given as the compulsory recovery or with plural suction recoveries, there is currently no method or apparatus which allows an effective recovery processing in a short time, but the measure is only taken with a combination of complex processings.